I have no idea, but just do a web search on [Castrol Transmax spec sheet]. The product information/spec sheet for the Transmax fluid should give the specifications it meets.
I keep telling people, particularly over time, that you have to look to the lubricant specifications, not the specific brands or fluid names a given brand currently sells. If it meets (or exceeds) the two noted Allison specs (and their newer 668 spec exceeds both of the noted ones) and/or the Dexron III/Mercron spec, and is a full synthetic formulation you're good.
You are likely to have to go through this process again, at some point in the future, when what's on the market now is no longer on the market. It's an essential skill related to antique car ownership.
A Bentley Arnage requires some rather unusual fluids. They are quite expensive to buy from the dealer or the usual sources. The car's manual isn't a great help to find alternatives for known reasons. This is a short thread to summarize the choices I’ve made for my Arnage T MY 05. Hydraulic...
I am using Castrol Dexron Transmax which is the highest evolution Dexron III H / synthetic
If you have GM transmission 4 speed 4L80 E , this is in my opinion the best and latest you could put as after its directly Dexron VI
If you have a ZF trnasmission, Dexron III H will do it but you could and should upgrade
My go to vehicle for checking the correct ATF for my Bentley and Jaguars with the 4L80E is a 99 Suburban 2500. This is what's recommended. I don't think you can go wrong with genuine synthetic fluid at under $28/gallon